HAMR recording head having a sloped wall pole
An apparatus includes a waveguide having an end adjacent to an air bearing surface, first and second poles positioned on opposite sides of the waveguide, and wherein the first pole includes a first portion spaced from the waveguide and a second portion extending from the first portion to the air bearing surface, with the second portion being structured such that an end of the second portion is closer to the waveguide than the first portion.
Latest Seagate Technology LLC Patents:
This invention was made with United States Government support under Agreement No. 70NANB1H3056 awarded by the National Institute of Standards and Technology (NIST). The United States Government has certain rights in the invention.
FIELD OF THE INVENTIONThis invention relates to magnetic recording heads, and more particularly to such recording heads for use in heat assisted magnetic recording devices.
BACKGROUND OF THE INVENTIONIn thermally assisted magnetic recording, information bits are recorded on a data storage medium at elevated temperatures, and the heated area in the storage medium determines the data bit dimension. In one approach, a beam of light is condensed to a small optical spot onto the storage medium to heat a portion of the medium and reduce the magnetic coercivity of the heated portion. Data is then written to the reduced coercivity region.
Heat assisted magnetic recording (HAMR) has been developed to address instabilities that result from a reduction in grain size in magnetic recording media. HAMR generally refers to the concept of locally heating a storage medium to reduce the coercivity of the storage medium so that an applied magnetic writing field can more easily direct the magnetization of the storage medium during the temporary magnetic softening of the storage medium caused by the heat source. Heat assisted magnetic recording allows for the use of small grain media, which is desirable for recording at increased areal densities, with a larger magnetic anisotropy at room temperature to assure sufficient thermal stability.
One example of a recording head for use in heat assisted magnetic recording generally includes a write pole and a return pole magnetically coupled to each other through a yoke or pedestal, and a waveguide for focusing light onto the storage medium. One of the most challenging design requirements for an integrated HAMR head is in positioning the magnetic poles with respect to the focused spot in the waveguide. Magnetic materials such as alloys of Fe, Co and Ni are poor optical materials, so they cannot be positioned in close proximity with the waveguide for an appreciable distance.
There is a need for a magnetic pole design that reduces the probability of adjacent track writing and data destabilization.
SUMMARY OF THE INVENTIONIn one aspect, this invention provides an apparatus including a waveguide having an end adjacent to an air bearing surface, and first and second poles positioned on opposite sides of the waveguide, wherein the first pole includes a first portion spaced from the waveguide and a second portion extending from the first portion to the air bearing surface, with the second portion being structured such that an end of the second portion is closer to the waveguide than the first portion.
The magnetic saturation of the second portion of the first pole can vary in a down track direction, either discretely using layers having different magnetic saturation, or continuously. The second portion of the first pole can have various cross-sectional shapes, and can include a plurality of sections.
The second pole can include a protrusion extending toward the second portion of the first pole at the air bearing surface. A near field transducer can be positioned in a core layer of the waveguide.
This invention encompasses various devices used for heat assisted magnetic recording.
For heat assisted magnetic recording (HAMR), an electromagnetic wave of, for example, visible, infrared or ultraviolet light is directed onto a surface of a data storage medium to raise the temperature of a localized area of the medium to facilitate switching of the magnetization of the area. Recent designs of HAMR recording heads include a thin film waveguide on a slider to guide light to the storage medium for localized heating of the storage medium. To launch light into the waveguide, a grating coupler can be used.
An insulating material 132 separates the coil turns. Another layer of insulating material 134 is positioned adjacent to the top pole. In one example, the substrate can be AlTiC, the core layer can be Ta2O5, and the cladding layers (and other insulating layers) can be Al2O3.
The structure of
Finite Element Modeling was used to predict the field from the head of
In one example of the graded sloped pole piece, a first layer of the pole piece that is close to the waveguide core layer can be 100 nm of 1.9 T CoNiFe. A second layer that is adjacent to the first layer can be 100 nm of 1.0 T NiFe. A third layer that is adjacent to the second layer can be 50 nm of 0.5 T NiCu. A fourth layer that is adjacent to the third layer can be 50 nm of 0.3 T NiCu. A fifth layer that is adjacent to the fourth layer can be 50 nm of 0.1 T NiCu.
In another example, the first layer can be 50 nm of 2.4 T FeCo plus 50 nm of CoNiFe. Then the second through fifth layers would be as described above.
In one example, the five layer graded Ms sloped pole design includes layers having a Ms of: 0.1, 0.55, 1, 1.45 and 1.9 T for the curves labeled Ms=1.9 T; and 0.1, 0.55, 1, 1.9 and 2.4 T for the curves labeled Ms=2.4 T in
The shape of the sloped pole piece as it extends from the pole body to the ABS can be varied.
It should be apparent that various aspects of the above designs could be combined with one another. For example, the trapezoidal pole can be constructed as a graded Ms pole piece.
To prevent corrosion of the seed layer, the high moment (corrosive) seed layer can be capped with a very thin NiFe layer. This NiFe layer needs to be kept very thin if the material being plated on top of the seed layer has a moment >>1.0 Tesla. If the NiFe layer is too thick, the flux will escape from the pole at this point and cause a spike in the field under the pole. If the material being plated on top of the high moment seed layer is ˜1.0 Tesla, the NiFe layer can be thicker. If the moment of the material being plated is <<1.0 Tesla, a different, more corrosion resistant material may be chosen as the capping layer, such as a Ni rich NiFe, CoNi or CoNiFe alloy. In one example, layer 150 may be a seed layer and a capping layer could be between layers 150 and 148. In another example, layers 150 and 148 could be seed layers and the capping layer could be between 148 and 146.
Some examples of material sets that can be used to construct the sloped pole piece are alloys including a first material “A” and a second material “B”, where A=Cu, Au, Ag or a combination of these three; and B═Fe, Co, Ni or a combination of these three. The alloy would be a mix of A and B materials. There could be multiple components of either A or B. The difference between the A and B materials is that the A materials are more noble than the B materials, which allows for the adjusting of the composition. The moment (4πMs) can be changed by changing the content of A. Increasing the A content can decrease moment.
While the invention has been described in terms of several examples, it will be apparent to those skilled in the art that various changes can be made to the described examples without departing from the scope of the invention as set forth in the following claims.
Claims
1. A recording head comprising:
- a waveguide having an end adjacent to an air bearing surface; and
- a write pole and a return pole positioned on opposite sides of the waveguide;
- wherein the write pole includes a first portion spaced from the waveguide and a second portion extending from the first portion to the air bearing surface, with the second portion being structured such that an end of the second portion is closer to the waveguide than the first portion, and wherein the second portion comprises an alloy including at least one of Cu, Au or Ag and at least one of Fe, Co or Ni.
2. The recording head of claim 1, wherein the second portion has a uniform cross-sectional shape.
3. The recording head of claim 2, wherein the shape is rectangular.
4. The recording head of claim 1, wherein the second portion is positioned at an angle with respect to a core layer in the waveguide in the range of about 15° to about 70°.
5. The recording head of claim 1, wherein the first portion is separated from a core layer in the waveguide by at least 500 nm.
6. The recording head of claim 1, further comprising:
- a coil having conductors positioned adjacent to the waveguide and on an opposite side of the waveguide from the write pole.
7. The recording head of claim 1, further comprising:
- a near field transducer.
8. The recording head of claim 1, further comprising:
- a mirror positioned adjacent to the waveguide.
9. The recording head of claim 8, wherein the mirror is positioned adjacent to a side of the waveguide opposite the write pole.
10. The recording head of claim 1, wherein the thickness of the second portion is smaller than the thickness of the first portion.
11. An recording head comprising:
- a planar waveguide including a core layer and first and second cladding layers on opposite sides of the core layer, and having an end adjacent to an air bearing surface; and
- a write pole and a return pole positioned on opposite sides of the waveguide;
- wherein the write pole includes a first portion spaced from the waveguide and a second portion extending from the first portion to the air bearing surface, with the second portion being structured such that an end of the second portion is closer to the waveguide than the first portion and wherein the second portion is positioned in the first cladding layer and at an angle with respect to the core in the range of about 15° to about 70°.
12. The recording head of claim 11, wherein the second portion comprises an alloy including at least one of Cu, Au or Ag and at least one of Fe, Co or Ni.
13. The recording head of claim 11, wherein the second portion has a uniform cross-sectional shape.
14. The recording head of claim 13, wherein the shape is rectangular.
15. The recording head of claim 13, further comprising:
- a mirror positioned adjacent to the waveguide.
16. The recording head of claim 15, wherein the mirror is position adjacent to a side of the waveguide opposite the write pole.
17. The recording head of claim 11, wherein the thickness of the second portion is smaller than the thickness of the first portion.
18. The recording head of claim 11, further comprising:
- a coil having conductors positioned adjacent to the waveguide and on an opposite side of the waveguide from the write pole.
19. The recording head of claim 11, further comprising:
- a near field transducer.
5333086 | July 26, 1994 | Frey et al. |
5831792 | November 3, 1998 | Ananth |
6721131 | April 13, 2004 | Litvinov et al. |
6721138 | April 13, 2004 | Chen et al. |
6771464 | August 3, 2004 | Minor |
6822829 | November 23, 2004 | Minor et al. |
6982932 | January 3, 2006 | Sakakima et al. |
7791839 | September 7, 2010 | Olson et al. |
8059374 | November 15, 2011 | Zhao et al. |
8119265 | February 21, 2012 | Hsia et al. |
20030235121 | December 25, 2003 | Eppler |
20040001420 | January 1, 2004 | Challener |
20040008591 | January 15, 2004 | Johns et al. |
20040062503 | April 1, 2004 | Challener |
20050052771 | March 10, 2005 | Rausch et al. |
20050078565 | April 14, 2005 | Peng et al. |
20050111309 | May 26, 2005 | Peng |
20050122850 | June 9, 2005 | Challener et al. |
20050135008 | June 23, 2005 | Challener et al. |
20050190682 | September 1, 2005 | Gage et al. |
20050289576 | December 29, 2005 | Challener |
20060119983 | June 8, 2006 | Rausch et al. |
20060143635 | June 29, 2006 | Liu et al. |
20060187564 | August 24, 2006 | Sato et al. |
20060222904 | October 5, 2006 | Hsia et al. |
20070139818 | June 21, 2007 | Shimazawa et al. |
20070165495 | July 19, 2007 | Lee et al. |
20070242396 | October 18, 2007 | Shimazawa et al. |
20080170319 | July 17, 2008 | Seigler et al. |
20080278864 | November 13, 2008 | Zhang et al. |
20100177449 | July 15, 2010 | Zhao et al. |
20120009337 | January 12, 2012 | Zhang et al. |
20120045662 | February 23, 2012 | Zou et al. |
20120113541 | May 10, 2012 | Hsia et al. |
Type: Grant
Filed: Sep 19, 2007
Date of Patent: Oct 16, 2012
Patent Publication Number: 20090073858
Assignee: Seagate Technology LLC (Scotss Valley, CA)
Inventors: Michael Allen Seigler (Pittsburgh, PA), Sharat Batra (Wexford, PA), Robert Earl Rottmayer (Wexford, PA), Hua Zhou (Pittsburgh, PA), Thomas William Clinton (Pittsburgh, PA), Jie Gong (Pittsburgh, PA)
Primary Examiner: Allen Cao
Attorney: Hall Estill Attorneys at Law
Application Number: 11/857,498
International Classification: G11B 5/127 (20060101);